1. Field of the Invention
This invention relates to portable terminal equipment, such as PHS and portable telephones, and a method of controlling backlight display therein, and, in particularly, relates to portable terminal equipment and a method of controlling backlight display therein which allows an extended operating life of a battery therein.
2. Description of the Prior Art
Conventionally, PHS and portable telephones are configured to operate using a battery as their electrical power source. When the amount of remaining power of the battery is lowered to a predetermined level, alarms or displayed massages or others notify the users that the amount of remaining battery power is limited.
When receiving the notification, the users turn the power off depending on the situation.
When alarms or displayed massages or others notify the users of the limited amount of remaining battery power in the conventional portable terminal equipment such as PHS and portable telephones described above, then the equipment has a little amount of available remaining battery time thereafter. So, it is preferable to turn the power off. Therefore, even if more conversation or a long-time standby state is necessary, the power may be sometimes set to OFF.
Thus, Japanese Patent Laid-Open No. 11-184576 discloses a technique in which, when the amount of remaining battery power is reduced, functions are stopped except for voice communications thereby allowing longer continuation of conversations or standby state.
However, according to the disclosure of the above specification, because other functions than voice communications are stopped when the amount of remaining battery power is reduced, information can not be displayed on the display device. So, there is a problem that the functions established in the terminal equipment can not be sufficiently used.
3. Object of the Invention
In view of the problem associated with the conventional techniques as described above, this invention has been performed. An object of the invention is to provide portable terminal equipment and a method of controlling backlight display therein which permit to extend the operating life of a battery therein while the functions established in the equipment remain sufficiently available, when the amount of remaining battery power is limited.
In order to achieve the object described above, the present invention provides portable terminal equipment comprising at least;
displaying means provided with multiple-color light emitting elements used as a backlight and displaying information,
a battery operating as an electrical power source,
monitoring means for monitoring the amount of remaining power of the battery,
driving means for driving the multiple-color light-emitting elements, and,
controlling means for generating and outputting a pulse for the light-emitting elements to be driven by the driving means,
wherein the controlling means, based on the result of monitoring in the monitoring means, generates and outputs a pulse for the emitting elements to be driven by the driving means.
Also, the controlling means corrects its generating pulse for the light emitting device to be driven by the driving means to a narrower pulse, when the result of monitoring in the monitoring means indicates that the amount of remaining battery power is lower than a predetermined level.
Further, the controlling means causes the driving means to drive a color light emitting element operable with lower power consumption of the multiple-color light emitting elements, when the result of monitoring in the monitoring means indicates that the amount of remaining battery power is lower than a predetermined level.
Still further, the controlling means includes a charging circuit for charging the battery with an externally supplied current.
Further, the displaying means is a liquid crystal display.
Further, a method of controlling backlight display for portable terminal equipment in which a backlight is lit by causing light-emitting elements to emit light in displaying means for displaying information comprises the steps of;
determining the width of a pulse causing said light-emitting elements to emit light,
monitoring the amount of remaining power of a battery in said portable terminal equipment,
when the result of said monitoring indicates that the amount of remaining power of said battery is higher than or equal to a predetermined level, causing the light-emitting elements to emit light with a pulse having said determined width, and
when the result of said monitoring indicates that the amount of remaining power of said battery is lower than the predetermined level, causing the light-emitting elements to emit light with the pulse having a narrower width than said determined width.
Further, a method of controlling backlight display for portable terminal equipment in which a backlight is lit in a desired color by causing a desired light emitting element of a plurality of light emitting elements to emit light in displaying means for displaying information comprises the steps of,
monitoring the amount of remaining power of a battery for said portable terminal equipment,
when the result of said monitoring indicates that the amount of remaining power of said battery is higher than or equal to a predetermined level, causing said desired light emitting element to emit light, and
when the result of said monitoring indicates that the amount of remaining power of said battery is lower than the predetermined level, causing a lower power light-emitting element of the plurality of light-emitting elements to emit light.
(Operation)
In the present invention configured as described above, when a backlight is to be lit, a pulse for driving light-emitting elements used as a backlight is generated in controlling means. Then, the width of a pulse to be generated is determined based on the amount of remaining power of a battery that is monitored by monitoring means. When the amount of remaining power of the battery is higher than or equal to a predetermined level, the width of a pulse to be generated is a width determined to light the backlight. On the other hand, when the amount of remaining power of the battery is lower than the predetermined level, the width of a pulse to be generated is made narrower than the width determined to light the backlight.
As a result, when the amount of remaining power of the battery is reduced to lower than a predetermined level, the quantity of current flowing through the light emitting elements is reduced, and thus their power consumption can be reduced.